Also, non-power-of-two dumps can be used to get a driver going; people are generally more likely to get you un-soldered flash chips when they know it's gonna contribute to emulation.
I've seen quite a lot of people consider the non-power of 2 roms to be more correct than what we have anyway, because they're what gets programmed into the chips in many cases, with the rest of the rom not even being cleared (so thus could contain random data in the actual chips.. This is especially true of flash based ones where you don't have to erase the entire rom first.
(also flash dumps containing the extra error correction data, which some systems need / use for general purpose storage also won't be power of 2, see the cv1k flash roms for example)
